Automatic gear checker for internal gears



April 18, 1967 c. H. MOTZ ET AL 3,314,157

AUTOMATIC GEAR CHECKER FOR INTERNAL GEARS Filed Jan. 24, 1966 2Sheets-Sheet 1 Ill INVENTORS CARL H. MOTZ April 18, 1967 Q MOTZ ET AL3,314,157

' AUTOMATIC GEAR CHECKER FOR INTERNAL GEARS Filed Jan. 24, 1966 2Sheets-Sheet 23 as INVE 48 CARL H. MOTZ 54 ysa. w. ANT 1y 7 6o awa j %W60 FIG;6. 50

A %TTORNYS United States Patent 3,314,157 AUTOMATIC GEAR CHECKER FORINTERNAL GEARS Carl H. Motz, Harper Woods, and Russel W. Anthony,

Detroit, Mich, assignors to National Breach & Ma-

chine Company, Detroit, Mich., a corporation of Michigan Filed Jan. 24,1966, Ser. No. 522,725 11 Claims. (Cl. 33179.5)

This is a continuation-in-part of application Ser. No. 267,745, filedMar. 25, 1963 now Patent No. 3,280,467.

The present invention relates to an automatic gear checker for internalgears.

It is an object of the present invention to provide an internal gearchecker having three pinions at least one of which is movable toward andaway from the other two in order to position the pinions close enoughtogether to receive the work gear, after which outward movement of thepinion or pinions brings all of the pinions into check meshingengagement with the internal gear.

It is a further object of the present invention to provide a checker foran internal gear comprising three pinions adapted to mesh simultaneouslywith the internal gear, and means responsive to movement of one of saidpinions toward and away from the other two to provide a measurement of agear condition.

It is a further object of the present invention to provide a checker foran internal gear as described in the preceding paragraph, comprisingmeans for driving the internal gear and pinions in rotation.

\ It is a further object of the present invention to provide an internalgear checker comp-rising three pinions mounted with their axes paralleland adapted to engage in full mesh with an internal work gear, in whichall of said pinions are angularly movable about axes radial with respectto the gear.

It is a further object of the present invention to provide an internalgear checker comprising a plurality of pinions adapted to engage in fullmesh with the teeth of an internal gear, in which one of the pinions ismounted for swiveling movement about an axis radial with respect to theinternal gear, and means for measuring the angular position of said onepinion about its swivel axis as a measurement of the helix angle of theinternal gear.

It is a further object of the present invention to provide an internalgear checker comprising means for supporting an internal gear forrotation, means for positioning three internal pinions in full mesh withthe teeth of the gear, means mounting one of said pinions for movementradially of the internal gear, and means responsive to such radialmovement to determine size, out-of-round, and tooth-to-tooth spacing ornicks on the teeth of the gear.

It is a further object of the present invention to pr0- vide an internalgear checker comprising three rotatable master pinions, automaticloading mechanism comprising a transfer platform for moving an internalgear into position surrounding said pinions, means for thereafterefiecting radial outward movement between said pinions to bring about acondition of full mesh between the teeth of the internal gear andpinions, means for driving the internal gear and pinions in rotation,means mounting one of the pinions for movement radially with respect tothe internal gear, measuring means responsive to movement of said onepinion, means for moving said pinions toward each other to produceclearance between said pinions and internal gear at the end of achecking cycle, means for thereafter lowering said platform, and meansfor thereafter advancing a second internal gear onto the of travel ofthe gears.

platform in such a way as to push the previously checked internal gearoff of the platform.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, illustrating preferred embodiments of theinvention, wherein:

FIGURE 1 is a plan view of the internal gear checker with parts omittedfor clearness.

FIGURE 2 is a side elevation of the gear checker shown in FIGURE 1, withcertain parts angularly displaced for clarity.

FIGURE 3 is an enlarged fragmentary view, with parts in section, showingthe mounting for one of the pinions.

FIGURE 4 is an enlarged fragmentary view, partly in section, showingcertain details of spring biasing means and pinion mounting means.

FIGURE 5 is a perspective view showing a portion of the automaticloading mechanism.

FIGURE 6 is a fragmentary section on the line 6-6, FIGURE 4.

FIGURE 7 is a schematic view of a modification of the present invention.

The checking mechanism for internal gears comprises a stationary framestructure comprising a plate 10 and a plate 12 rigidly interconnected bysupport members 14 and 16. Mounted on the upper plate 12 are separatesupport means for three master pinions designated respectively, P1, P2and P3. Means later to be described are provided for shifting thesepinions inwardly toward the vertical center line of the machine, thiscenter line being designated C, to a position which permits an internalgear to be moved freely into position surrounding said pinions, afterwhich the pinions are movable radially outwardly from the center lineinto positions of full mesh with respect to the work gear G. While thepinions are in full mesh with the work gear, one of the pinions isdriven in rotation to effect a predetermined rotational movement of theinternal gear, preferably at least 360 degrees. After the checkingoperation is complete the master pinions are moved inwardly and thechecked gear is moved out of surrounding relation with respect thereto.

The movements of the work gears into and out of the checking relation istaken care of by automatic loading mechanism best illustrated in FIGURES2, 4 and 5. The work gears are advanced in a chute 20 into alignmentwith an angularly disposed chute 22 comprising a pair of laterallyspaced rails 22a and 22b. The chute 22 is provided with a slidablefeeding member 23 actuated by a push rod 24 and adapted to engage a workgear at the juncture between chutes 20 and 22, and to advance it to aposition in which it is disposed directly below the position which itwill occupy in the checking cycle. In order to provide accuracy inregistration of the work gearin this position a pair of spring pressed!shoes 26and 28 are .provided, compression springs 30 uring the shoesinwardly. Each of the shoes is guided for inward movement by means of arod 32 slidable in. a bracket 34, and inward movement is limited by nuts35 on the outer threaded ends of rods 32. The internal gears aresequential-1y lifted into checking relation with the pinions by means ofa wobble plate 36 which is supported on a ball pivot 38 at the upper endof a lift shaft 40 operable by suitable means such for example as .afluid cylinder. The plate 36 is a circular disc dimensioned to passbetween the rails and in its lowermost position it is beneath the pathWhen a gear is pushed to located .position between the locating shoes 26and 28, the wobble plate 36 is raised moving a work gear G into checkingposition, as best illustrated in FIGURE 4. It will be observed in thisfigure that the work gears G as shown are provided with counterbores toprovide locating surfaces extending perpendicular to the axes of thework gears, and that these locating surfaces rest upon the upper surfaceof the wobble plate 36.

It will be observed in this figure that the work gear is also providedwith vertically extending surfaces spaced slightly from the outerperiphery of the platform 36, thus permitting limited lateral ortransverse movement of the gear relativeto the platform as requiredduring the checking operation.

When a gear has been completely checked, the wobble plate with the gearthereon is lowered to position the work gear in the same horizontalplane as the remaining gears in the chutes 2t and 22, at which time anew internal gear is pushed onto the wobble plate and located by theshoes 26 and 28. This operation pushes the previously checked internalgear off of the wobble plate into a discharge portion of the chute 22.

The structure for mounting and moving the master pinions P1, P2 and P3is generally similar except for the mounting of the master pinion P1whose movement is employed in the checking operation. Accordingly, onlyone of the pinion mounting structures will be described in detail.

As best seen in FIGURE 4, there is provided a ball bush or mounting 42having ball bearings 44 therein supporting a shaft 46 for both axialmovement and rotational movement in the ball bush. At its inner end theshaft 46 is reduced as indicated at 48 and is provided with flats 50 thepurpose of which is apparent from an inspection of FIGURE 6. A bracket52 is provided having an opening 54 therein for receiving the reducedend 48 of the shaft 46. The bracket is split as indicated at 56 and isprovided with a clamping screw 58. When the screw 58 is loosened, thebracket may be angularly adjusted on the shaft portion 48 byrespectively tightening and loosening the set screws 60.

The bracket 52 includes an offset journal portion 62 in which isjournaled a shaft 64, the shaft carrying one of the master pinions, andin FIGURE 4, the master pinion P1, thereon.

Extending upwardly from the ball bush 42 is a centering housing 66details of which are best seen in FIGURE 3. This housing has atransverse through opening 63 therein through which extends an arm 70,the inner end of the arm being fixed to the bracket 52. The arm 70 iscentered in the enlarged opening 68 by centering pins 72, the pins 72being engaged by centering springs 74 which operate to maintain the arm70 centered except when displaced from centered position by rotation ofthe bracket 52 about the axis of its mounting shaft 46.

At its outer end the arm 70 carries a spring seat 76 and a compressionspring 77 extends between the spring seat 76iand the housing 66, thusurging the bracket 52 radially outwardly from the center line C of thechecker.

The aforementioned mounting of the pinion P1 permits swiveling of thepinion P1 about the axis of the shaft 46, which is radial with respectto the center line of the machine.

Referring again to FIGURE 4, it will be observed that at its outer endthe shaft 46 is reduced to provide a shoulder 82 and a bar 84 is clampedagainst this shoulder by a nut 86. As the shaft 46 is moved axially inresponse to certain characteristics of the internal gear G, the bar 84will transmit this motion to various checking instrumentalities, suchfor example as a device 88 for checkingthe out-of-round condition of thegear, a device 90 forchecking size of the gear, and a device 92 whichchecks nicks or abrupt tooth-to-tooth spacing errors. The checkingdevice 92 may be an inertia ty-pe device responsive only to relativelyabrupt movement.

An additional check is provided by the wobble plate 36 and for thischeck there is provided an indicator 94 having a plunger 95 engageablewith the upper surface of the wobble plate 36. Thus, as the gear isdriven in rotation, as will subsequently appear, the wobble platerotates 4- with it and any out of true condition of the flat locatingsurface in the counterbore of the work gear will produce an indicationon the indicator 94.

In addition, means are provided for measuring the helix angle ordetermining helix angle error in the teeth of the work gear. For thispurpose an indicator 96 is mounted on a bracket 97 secured to themounting 42. The indicator 96 has a plunger 98 adapted to engage theupper surface of the bar 84 adjacent one end thereof. It will berecalled that the bar 84 is rigidly aflixed to the shaft 46 and at itsother end of the shaft 46. has the pinion mounting bracket 52 fixedthereto in a position which is adjustable by means of the set screws 60.Accordingly, if the bracket 52 is adjusted so that the arm 70 isaccurately centered and the indicator 96 set to zero when the pinion P1is in full mesh with the gear G, any variation in helix angle of aportion of the teeth of the gear G or of the teeth of subsequentlychecked work gear, will cause rotation of the shaft 46 and inclinationof the bar 84, thus producing a change in the reading of the indicator96.

It may be mentioned at this time that while indicators have been shownas conventional dial indicators actuated by plungers, it is to beunderstood that indicators of any type, either mechanical or electrical,may be employed.

Means are provided for rotating one of the pinions, as for example thepinion P2, and this means comprises a motor 100 connected by a shaft 102and loose spline couplings 104 with a worm 106 engageable with a wormgear 108 connected to a shaft similar to the shaft 64 of FIG- URE 4 butextending upwardly. In FIGURE 2 the housing, here designated 62a, isindicated as extending upwardly to a greater extent than does thehousing 62. All of the pinions P1, P2 and P3 are mounted for angularadjustment about axes radial with respect to the center line of thechecker, in the same manner as described in detail for the pinion P1.Thus, if errors are present in the helix angle of the teeth of theinternal gear, this will permit the pinions to adjust themselves so thatthe helix angle error will not influence checking of other gearcharacteristics. As previously described however, this swivelingmovement of the pinion P1 is measured to provide a check as to the helixangle of the teeth of the internal gear.

In the cycle of the machine, which is repeated automatically so as toproduce automatic checking of a sequence of gears, means are providedfor shifting all of the pinions radially inwardly to provide clearancefor insertion and removal of the internal gears into the plane of thepinions P1, P2 and P3. For the checking pinion P1, this radial movementis controlled by a solenoid 110 having a plunger 112 connected by aspring 114 to a lever 116 pivoted as indicated at 113 to a post 120. Atits upper end the lever 116 carries a roller 122 which is engageablewith the outer end of the shaft 46.

The remaining two brackets 52 are also provided with spring means 77a,similar to spring means 77 previously described, but substantiallystronger to insure location of pinions P2 and P3 by abutments to besubsequently described, urging them outwardly, and solenoid means asseen at 124 for urging the pinions inwardly into clearance position whenthe solenoids are energized. The position of the pinions P2 and P3 whenthe solenoids 1-24 are deenergized is determined by an abutment 125carried by a bracket 126 and engageable by the radially outer ends ofarms 127 corresponding to the arm 70 associated with the pinion P1.Thus, when the solenoids 124 are deenergized the pinions P3 and P2 arespring biased into predetermined positions. At this time the pinion P1,which is mounted for radial movement with respect to the center line Cof the checker, is spring urged into full mesh engagement with the gearG and maintains the gear in full mesh with the locating pinions P2 andP3.

In the automatic cycle the solenoids 110 and 124 are energized to movethe pinions inwardly into clearance position. Suitable means areprovided for de-energizing the solenoids when the wobble plate 36 hasmoved the Work gear G into partially overlapping relation with respectto the pinions P1, P2 and P3. At this time the pinions P2 and P3 remainin a fixed position and the pinion P1 is movable radially with respectto the center line C of the checker in accordance with variations incharacteristics of the gear G. At the end of the checking cycle, whenthe pinion P2 has driven the gear G through at least 360 degrees ofrotation, the solenoids are again energized, moving the pinions inwardlyinto clearance and at the same time the wobble plate is moved quicklydownwardly into a position in which the checked gear may be dischargedand a new gear positioned thereon.

When the gear to be checked is fully meshed with the pinions P1, P2 andP3 it is supported by the pinions in a horizontal plane and if helixangle error exists, the pinions swivel as required about radial axes toaccommodate themselves to helix angle error. Rotation of the Work gearat this time will accordingly result in radial motion of the checkingpinion P1, the pinions P2 and P3 remaining fixed against radialdisplacement and thus providing an indicating location for the workgear.

If ovality or out-of-round exists with respect to the work gear, theshaft 46 will move slowly and the indicator 83 will measure and recordthe departure from a true circular condition. If the gear G is over orundersized, this will be determined by the measuring device 90. Ifabrupt movement is imparted to the shaft 46 as by tooth-to-tooth spacingerrors or nicks, the indicator 92 will respond. Any deviation fromproper helix angle will be measured and if desired, recorded by theindicator 96. If the locating surface formed by the bottom of thecounterbore on the gear is not in line, this condition will be observedby the indicator 94 as a result of movement of the wobble plate 36.

It will of course be understood that the measurements of the variousgear characteristics may be recorded by conventional means if desiredand that further, departure from acceptable limits as to the variousgear character,- istics may if desired actuate means for sorting thechecked gears into categories consistent with the observed deviations.

Referring now to FIGURE 7 there is schematically illustrated a variationin arrangement of the parts. Pinions P4, P5, and P6 are supported onbrackets 152 and movement of the bracket supporting the pinion P4 istransmitted by shaft 146- to bar 134, corresponding to the shaft 46 andbar 84 seen in FIGURE 4. In this case the work gear G as before, isengaged with a checking master pinion designated P4 which is mounted onthe bracket 152. It is found that the determination of size of thepinion and out-of-round conditions thereof can be measured much moreaccurately if one of the locating pinions, as for example the pinion P5,is located 180 degrees from the pinion P4, or in a positiondiametrically opposite thereto. In this case the third locating pinionP6 is positioned intermediate the pinions P4 and P5, or spaced 90degrees from each other. It will be understood that if only two pinionsare provided, such as the pinions P4 and P5, located 180 degrees apart,the gear G is not sufliciently stabilized against movement transverse toa line joining the pinions P4 and P5. For this reason the stabilizingpinion P6 is provided which of course stabilizes the gear G againstmovement downwardly as viewed in the figure. However, the pinion P6alone affords no stability against movement upwardly as seen in FIGURE7. Accordingly, with the pinions P5 and P6 in the position shown inFIGURE 7, proper stability to the gear is provided by a roller 130suitably connected to an actuator which may be in the form of a solenoid132 capable of retracting the roller 130 into a clearance position forloading and unloading the gear and for releasing the roller 130 forspring pressed engagement with the outer cylindrical surface of the gearG. Because the roller 130 is located intermediate the pinions P5 and P6it maintains the gears in full mesh with the pinions P5 and P6 and thus,provides accurate location thereof. The pinion P4 is radially movable asbefore and is connected to the bar 184 which transmits movement of thechecking pinion P4 to instruments for measuring and/or recordingvariations in gear characteristics. It will be understood that thepinions P5 and P6 are connected to suitable means such as solenoidssimilar to the solenoids 124 previously described, to shift the pinionsinwardly to clearance position, together with means operable to locatethe pinions P5 and P6 in accurately predetermined locating position whenthe soleniods are de-energized.

It has further been found that with the arrangement of pinions P4, P5and P6 illustrated in FIGURE 7, in which the pinion P4 is the radiallymovable checking pinion, the pinions P5 and P6, which may have anoperationally fixed position, are sufficient to maintain the gear G inproper position without the provision of the external roller 130. Thus,employing either the pinion P5 or P6 as the driving pinion and byselecting its direction of rotation such that it operates to maintainthe gear G in tight mesh both with the drive pinion. and with the otheroperationally fixed pinion, use of the external roller may beeliminated.

In some cases it is desirable to eliminate the positive drive connectionto one of the pinions P4, P5 or P6, and this can be convenientlyaccomplished by providing means 134 to drive roller which in this casewill have a friction surface for driving the internal gear G.

The drawings and the foregoing specification constitute a description ofthe improved automatic gear checker for internal gears in such full,clear, concise and exact terms as to enable any person skilled in theart to practice the invention, the scope of which is indicated by theappended claims.

What We claim as our invention is:

1. An internal gear checker comprising three rotary pinion supportsspaced substantially equally from a common vertical centerline, saidsupports having pinions thereon occupying a substantially horizontalcommon plane with their axes substantially parallel to each other andperpendicular to said plane and adapted to enter into tight meshsimultaneously with an internal work gear having its axis substantiallycoincident with the vertical centerline, means mounting all of saidsupports for movement from an operating position radially inwardly withrespect to the centerline to loading positions in which the pinions haveradial clearance with respect to the internal work gear, means connectedto two of said supports to shift them radially between inwardlydisplaced loading positions and outward displaced fixedoperating-positions, means connected to the third support to shift itinwardly to loading position and to bias it outwardly to urge the pinionthereon yieldingly into tight mesh with an internal work gear positionedin said plane surrounding said pinions, conveyor means below the planecontaning said pinions including means for positioning an internal workgear with its axis vertical and substantially coincident with the saidvertical centerline, work gear support means engageable with theunderside of a work gear on said conveyor means to support the workgearfor limited lateral displacement, means connected to said gearsupport means for moving it vertically from the plane of said conveyormeans to the plane of said pinions, means for rotating said pinions, thework gearin mesh therewith, and said gear support, and means formeasuring movement of said third support during such rotation.

2. A gear checker as defined in claim 1 in whichsaid conveyor meanscomprises rails on which the work gears are slidable, and laterallymovable approximate locating means comprising members engageable withthe sides of gears as they are advanced to position said gears seriallywith their axes substantially coincident with the vertical centerline ofthe gear checker.

3. A gear checker as defined in claim 2 in which said locating meanscomprises stop means limiting inward movement of said members to preventgripping of a work gear therebetween so as to leave the work gears freefor veitical movement.

4. A gear checker as defined in claim 1 in which said work support meanscomprises a platform rotatable about said vertical centerline.

5. A gear checker as defined in claim 1 in which said platform ismounted for a universal wobble movement about a pivot point locatedcentrally thereof.

6. Apparatus for checking an internal gear having an imaginary verticalcenterline in which the internal gear is mounted with its axis verticaland substantially conicident with the centerline, three pinion supportsincluding means mounting pinions thereon for rotation in a commonhorizontal plane substantially coincident with the plane of the internalgear and in mesh therewith, pinions on said supports, means mounting afirst one of said pinion supports in a fixed operating position, meansmounting a second one of said pinion supports diametrically oppositesaid first pinion support for movement radially of the internal gear,means mounting the third one of said pinion supports in a fixedoperating position intermediate the operating positions of said firstand second pinion supports, means driving said first or third pinion inrotation thereby driving the internal gear in rotation and therebydriving the remaining two pinions in rotation, the direction of rotationof the pinion which drives the internal gear in rotation being thedirection which causes the work gear to remain in tight mesh with theother operationally fixed pinion, and means for measuring displacementof the support for said second pinion during rotation of the internalgear.

7.'Apparatus for use with an internal gear in which the gear is rotatedabout its axis comprising three rotary pinion supports for supportingthree pinions in a common horizontal plane with their axes vertical,pinions on said supports, means mounting said supports for movement insaid plane radially with respect to a centerline, said supports beingspaced substantially equidistant from said centerline, means forshifting said supports radially inwardly toward said centerline toclearance position with respect to the internal gear, a horizontalplatform movable vertically along said centerline adapted to receive aninternal. gear with its axis substantially coincident with saidcenterline, means for moving said platform to position the gear thereonin the horizontal plane of the pinions on said supports, means formoving two of said supports radially outwardly to fixed locatingpositions, means for urging the other of said supports radiallyoutwardly of centerline to maintain pinions on said supports in tightmesh with the internal gear, said platform being mounted for rotationabout a vertical axis and for limited wobble about a center on its axisof rotation, means for measuring the wobble of said platform duringrotation thereof, and means for driving the internal gear and pinions inrotation.

8. An internal gear checker comprising three rotary pinion supportshaving vertical axes, pinions on said supports, said supports beingmovable radially horizontally toward and away from a common verticalcenterline, a gear support platform movable vertically on saidcenterline, means for moving all of said supports radially inwardly toprovide clearance for all of said pinions with respect to an internalgear on said platform, means for thereafter moving two of said supportsradially outwardly to fixed locating positions, the third support beingfreely movable radially of said centerline, resilient means urging saidthird support radially outwardly, drive means for rotating said pinionsand the internal gear in mesh therewith, means mounting said platformfor rotation about a vertical axis and for wobble movement about acenter on said vertical axis, means for measuring Wobble of saidplatform during rotation thereof, and measuring means 8 responsive toradial movement of said third support during rotation of a gear on saidplatform as the result of meshed engagement with a pinion on said drivensupport.

9. An internal gear checker comprising three rotary pinion supportshaving vertical axes, pinions on said supports, said supports beingmovable radially horizontally toward and away from a common verticalcenterline, means mounting all of said supports for angular movementabout axes extending radially of said centerline and intersecting theaxes of rotation of said supports at the location there-on of pinionscarried thereby, a gear support platform movable vertically on saidcenterline, means for moving all of said supports radially inwardly toprovide clearance for all of said pinions With respect to an internalgear on said platform, means for thereafter moving two of said supportsradially outwardly to fixed locating positions, the third support beingfreely movable radially of said centerline, resilient means urging saidthird support radially outwardly, drive means for rotating said pinionsand the internal gear in mesh therewith, means mounting said platformfor rotation about a vertical axis and for wobble movement about acenter on said vertical axis, means for measuring wobble of saidplatform during rotation thereof, and measuring means responsive toradial movement of said third support during rotation of a gear on saidplatform as the result of meshed engagement with a pinion on said drivensupport.

10. Apparatus as defined in claim 9, and means for measuring the angularposition of one of said supports when a pinion thereon is in mesh withan internal gear on said platform.

11. An internal gear checker comprising first, second and third rotarypinion supports having pinions thereon occupying a common plane withtheir axes substantially parallel to each other and perpendicular tosaid plane and adapted to enter into tight mesh simultaneously with aninternal work gear to be checked, said first support being located infixed position during a checking operation, said second support beinglocated in diametrically opposed relationship from said first supportwith respect to the work gear, means mounting said second support formovement radially of the gear being checked directly toward and awayfrom the said first support, said third support being spacedcircumferentially of the work gear from both said first and secondsupports, said third support being located in fixed position during achecking operation, means yieldably engageable with the outside diameterof a work gear on said pinions at a zone intermediate said operationallyfixed first and third supports and effective to apply radially inwardpressure thereto to maintain the work gear in tight mesh with thepinions on said operationally fixed first and third supports, meansconnected to said second support and urging it radially outwardly of thework gear to maintain the pinion thereon in tight mesh with the workgear, means for driving said pinions and work gear in rotation, andmeans for measuring movement of said second support during rotation ofthe gear and pinions.

References Cited by the Examiner UNITED STATES PATENTS 1,637,482 8/1927Graves.

2,331,987 10/1943 Leatherman 33174 2,367,004 1/1945 Chitwood 33179.52,735,188 2/1956 Sunnen 33178 2,785,799 3/1957 Esken.

2,821,024 1/1958 Nyiand 33179.52 2,983,375 5/1961 Gates 33179.52 X3,048,926 8/1962 Johnson 33178 LEONARD FORMAN, Primary Examiner.

S. S. MATTHEWS, Assistant Examiner.

1. AN INTERNAL GEAR CHECKER COMPRISING THREE ROTARY PINION SUPPORTSSPACED SUBSTANTIALLY EQUALLY FROM A COMMON VERTICAL CENTERLINE, SAIDSUPPORTS HAVING PINIONS THEREON OCCUPYING A SUBSTANTIALLY HORIZONTALCOMMON PLANE WITH THEIR AXES SUBSTANTIALLY PARALLEL TO EACH OTHER ANDPERPENDICULAR TO SAID PLANE AND ADAPTED TO ENTER INTO TIGHT MESHSIMULTANEOUSLY WITH AN INTERNAL WORK GEAR HAVING ITS AXIS SUBSTANTIALLYCOINCIDENT WITH THE VERTICAL CENTERLINE, MEANS MOUNTING ALL OF SAIDSUPPORTS FOR MOVEMENT FROM AN OPERATING POSITION RADIALLY INWARDLY WITHRESPECT TO THE CENTERLINE TO LOADING POSITIONS IN WHICH THE PINIONS HAVEREDIAL CLEARANCE WITH RESPECT TO THE INTERNAL WORK GEAR, MEANS CONNECTEDTO TWO OF SAID SUPPORTS TO SHIFT THEM RADIALLY BETWEEN INWARDLYDISPLACED LOADING POSITIONS AND OUTWARD DISPLACED FIXED OPERATINGPOSITIONS, MEANS CONNECTED TO THE THIRD SUPPORT TO SHIFT IT INWARDLY TOLOADING POSITION AND TO BIAS IT OUTWARDLY TO URGE THE PINION THEREONYIELDINGLY INTO TIGHT MESH WITH AN INTERNAL WORK GEAR POSITIONED IN SAIDPLANE SURROUNDING SAID PINIONS, CONVEYOR MEANS BELOW THE PLANE CONTANINGSAID PINIONS INCLUDING MEANS FOR POSITIONING AN INTERNAL WORK GEAR WITHITS AXIS VERTICAL AND SUBSTANTIALLY COINCIDENT WITH THE SAID VERTICALCENTERLINE, WORK GEAR SUPPORT MEANS ENGAGEABLE WITH THE UNDERSIDE OF AWORK GEAR ON SAID CONVEYOR MEANS TO SUPPORT THE WORK GEAR FOR LIMITEDLATERAL DISPLACEMENT, MEANS CONNECTED TO SAID GEAR SUPPORT MEANS FORMOVING IT VERTICALLY FORM THE PLANE OF SAID CONVEYOR MEANS TO THE PLANEOF SAID PINIONS, MEANS FOR ROTATING SAID PINIONS, THE WORK GEAR IN MESHTHEREWITH, AND SAID GEAR SUPPORT, AND MEANS FOR MEASURING MOVEMENT OFSAID THIRD SUPPORT DURING SUCH ROTATION.